好久没有cisco了， 有些知识点都忘记了， 利用Cisco路由器做光纤线路和ADSL线路冗余，是很早以前做过的，那个时候是热点 ，现在不知怎样了 ， 不管怎样 ， 希望对关注这块的朋友，有些许的帮助。
          在前面http://terryyw.blog.51cto.com/365902/387006这篇文章中，两条线路都是光纤，这里一条是光纤，一条是ADSL,之所以没有谈负载均衡，是因为光纤和ADSL不是一个量级的，何谈负载均衡，这里只需做到互为冗余就可以了。

           以下为简单网络图：

            以下为配置：
#############################################################
adsl163#show run
Building configuration...
Current configuration : 1860 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname adsl163
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
no ip domain lookup
!
multilink bundle-name authenticated
!
!

username adsl163 privilege 15 password 0 adsl163
!
!
track 111 rtr 1 reachability
!
!
interface FastEthernet0/0
ip address 61.x.x.2 255.255.255.252
ip nat outside
ip virtual-reassembly
duplex auto
speed auto
!
interface FastEthernet0/1
description $ETH-WAN$
no ip address
duplex auto
speed auto
pppoe enable group global
pppoe-client dial-pool-number 1
!
interface FastEthernet1/0
ip address 192.168.1.1 255.255.255.0
ip nat inside
ip virtual-reassembly
duplex auto
speed auto
!
interface Dialer0
ip address negotiated
ip mtu 1452
ip nat outside
ip virtual-reassembly
encapsulation ppp
dialer pool 1
dialer-group 1
ppp authentication chap pap callin
ppp chap hostname a95xxxx
ppp chap password 0 terryywxxx
ppp pap sent-username a95xxx password 0 terryxxxx
!
ip route 0.0.0.0 0.0.0.0 61.x.x.1 track 111
ip route 0.0.0.0 0.0.0.0 Dialer0 60
!
!
ip http server
no ip http secure-server
ip nat inside source route-map 163 interface FastEthernet0/0 overload
ip nat inside source route-map adsl interface Dialer0 overload
!
ip access-list extended allip
permit ip any any
!
ip sla 1
icmp-echo 61.x.x.1
timeout 1200
frequency 3
ip sla schedule 1 life forever start-time now
dialer-list 1 protocol ip permit
!
!
!
route-map adsl permit 10
match ip address allip
match interface Dialer0
!
route-map 163 permit 10
match ip address allip
match interface FastEthernet0/0
!
!
control-plane
!
!
line con 0
logging synchronous
line aux 0
line vty 0 4
login
!
!
end
adsl163#
############################################################
在光纤线路断线后， ADSL线路立即接替其流量，待光纤线路恢复后，流量回到光纤线路。